Fischer-tropsch synthesis using microchannel technology and novel catalyst and microchannel reacotr

ABSTRACT

The disclosed invention relates to a process for converting a reactant composition comprising H 2  and CO to a product comprising at least one aliphatic hydrocarbon having at least about 5 carbon atoms, the process comprising: flowing the reactant composition through a microchannel reactor in contact with a Fischer-Tropsch catalyst to convert the reactant composition to the product, the microchannel reactor comprising a plurality of process microchannels containing the catalyst; transferring heat from the process microchannels to a heat exchanger; and removing the product from the microchannel reactor; the process producing at least about 0.5 gram of aliphatic hydrocarbon having at least about 5 carbon atoms per gram of catalyst per hour; the selectivity to methane in the product being less than about 25%. The disclosed invention also relates to a supported catalyst comprising Co, and a microchannel reactor comprising at least one process microchannel and at least one adjacent heat exchange zone.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a divisional of and claims priority under 35U.S.C. §120 to copending, commonly assigned U.S. application Ser. No.11/484,069, filed Jul. 11, 2006, which is a divisional of U.S.application Ser. No. 10/766,297, filed Jan. 28, 2004 (now issued as U.S.Pat. No. 7,084,180 B2), the disclosures of which are fully incorporatedby reference herein.

TECHNICAL FIELD

This invention relates to a Fischer-Tropsch synthesis process usingmicrochannel technology, and a novel catalyst and microchannel reactor.The catalyst and reactor are useful in Fischer-Tropsch synthesisprocesses.

BACKGROUND OF THE INVENTION

The Fischer-Tropsch synthesis reaction involves converting a reactantcomposition comprising H₂ and CO in the presence of a catalyst toaliphatic hydrocarbon products. The reactant composition may comprisethe product stream from another reaction process such as steam reforming(product stream H₂/CO˜3), partial oxidation (product stream H₂/CO˜2),autothermal reforming (product stream H₂/CO˜2.5), CO₂ reforming(H₂/CO˜1), coal gasification (product stream H₂/CO˜1), and combinationsthereof. The aliphatic hydrocarbon products may range from methane toparaffinic waxes of up to 100 carbon atoms or more.

Conventional reactors such as tubular fixed bed reactors and slurryreactors have various problems in heat and mass transfer resulting inlimitations of choice of process conditions for Fischer-Tropschsynthesis reactions. Hot spots in the fixed bed reactors significantlypromote methane formation, reduce the heavy hydrocarbon selectivity anddeactivate the catalyst. On the other hand, strong mass transferresistance inherent in a catalyst suspended in a slurry system generallyreduces the effective reaction rate and also causes difficulty inseparation of catalysts from the products. This invention provides asolution to these problems.

This invention relates to a process for conducting a Fischer-Tropschsynthesis reaction in a microchannel reactor wherein the one-passconversion of CO within the reactor is enhanced and the selectivity tomethane is reduced. With the inventive process the tendency to form hotspots in the microchannel reactor is reduced. This reduction in thetendency to form hot spots is believed to be due, at least in part, tothe fact that the microchannel reactor provides enhanced heat transfercharacteristics and more precise control of temperatures and residencetimes as compared to prior art processes wherein microchannel reactorsare not used. With this process, it is possible to obtain relativelyhigh levels of conversion of the CO and high levels of selectivity tothe desired product (e.g., hydrocarbons in the middle distillate range)as compared to such prior art. A novel catalyst as well as a novelmicrochannel reactor design are provided.

SUMMARY OF THE INVENTION

This invention relates to a process for converting a reactantcomposition comprising H₂ and CO to a product comprising at least onealiphatic hydrocarbon having at least about 5 carbon atoms, the processcomprising: flowing the reactant composition through a microchannelreactor in contact with a Fischer-Tropsch catalyst to convert thereactant composition to the product, the microchannel reactor comprisinga plurality of process microchannels containing the catalyst;transferring heat from the process microchannels to a heat exchanger;and removing the product from the microchannel reactor; the processproducing at least about 0.5 gram of aliphatic hydrocarbon having atleast about 5 carbon atoms per gram of catalyst per hour; theselectivity to methane in the product being less than about 25%.

In one embodiment, the heat exchanger comprises a plurality of heatexchange channels adjacent to the process microchannels. In oneembodiment, the heat exchange channels are microchannels.

In one embodiment, the invention relates to a catalyst comprising Cosupported on alumina, the loading of Co being at least about 25% byweight, the Co dispersion being at least about 3%. This catalyst mayfurther comprise Re, Ru or a mixture thereof.

In one embodiment, the invention relates to a catalyst, the catalystcomprising Co and a support, the catalyst being made by the steps of:(A) impregnating the support with a composition comprising Co to providean intermediate catalytic product; (B) calcining the intermediatecatalytic product formed in step (A); (C) impregnating the calcinedintermediate product formed in step (B) with a composition comprising Coto provide another intermediate catalytic product; and (D) calcining theanother intermediate catalytic product formed in step (C) to form thecatalyst, the catalyst having a Co loading of at least about 25% byweight. The composition comprising Co used in step (A) may be the sameas or it may be different than the composition comprising Co used instep (C). The support may comprise alumina.

In one embodiment, the invention relates to a microchannel reactor,comprising: at least one process microchannel, the process microchannelhaving an entrance and an exit; and at least one heat exchange zoneadjacent to the process microchannel, the heat exchange zone comprisinga plurality of heat exchange channels, the heat exchange channelsextending lengthwise at right angles relative to the lengthwisedirection of the process microchannel; the heat exchange zone extendinglengthwise in the same direction as the process microchannel and beingpositioned near the process microchannel entrance; the length of theheat exchange zone being less than the length of the processmicrochannel; the width of the process microchannel at or near theprocess microchannel exit being greater than the width of the processmicrochannel at or near the process microchannel entrance. In oneembodiment, the at least one heat exchange zone comprises a first heatexchange zone and a second heat exchange zone, the length of the secondheat exchange zone being less than the length of the first heat exchangezone.

BRIEF DESCRIPTION OF THE DRAWINGS

In the annexed drawings, like parts and features have like designations.

FIG. 1 is a schematic illustration of a microchannel that may be usedwith the inventive process.

FIG. 2 is a schematic flow sheet illustrating the inventiveFischer-Tropsch synthesis process in a particular form wherein areactant composition comprising CO and H₂ flows through a microchannelreactor in contact with a Fischer-Tropsch catalyst and reacts to form aproduct comprising at least one aliphatic hydrocarbon.

FIG. 3 is a schematic illustration of a layer of process microchannelsand a layer of heat exchange microchannels that may be used in themicrochannel reactor core of the microchannel reactor illustrated inFIG. 2.

FIG. 4 is a schematic illustration of a process microchannel and anadjacent heat exchange zone that may be used in the microchannel reactorcore of the microchannel reactor illustrated in FIG. 2, the heatexchange zone containing a plurality of heat exchange channels extendinglengthwise at right angles relative to the lengthwise direction of theprocess microchannel, the flow of heat exchange fluid through the heatexchange channels being cross-current relative to the flow of reactantcomposition and product through the process microchannel.

FIG. 5 is a schematic illustration of a process microchannel and anadjacent heat exchange channel that may be used in the microchannelreactor core of the microchannel reactor illustrated in FIG. 2, the flowof heat exchange fluid through the heat exchange channel beingcounter-current relative to the flow of reactant composition and productthrough the process microchannel.

FIG. 6 is a schematic illustration of a process microchannel and anadjacent heat exchange zone that may be used in the microchannel reactorcore of the microchannel reactor illustrated in FIG. 2, the heatexchange zone containing a plurality of heat exchange channels extendinglengthwise at right angles relative to the lengthwise direction of theprocess microchannel, the heat exchange zone extending lengthwise in thesame direction as the process microchannel and being positioned at ornear the process microchannel entrance, the length of the heat exchangezone being less than the length of the process microchannel.

FIG. 7 is a schematic illustration of a process microchannel and firstand second adjacent heat exchange zones that may be used in themicrochannel reactor core of the microchannel reactor illustrated inFIG. 2, each of the heat exchange zones containing a plurality of heatexchange channels extending lengthwise at right angles relative to thelengthwise direction of the process microchannel, the heat exchange zoneextending lengthwise in the same direction as the process microchanneland being positioned at or near the process microchannel entrance, thelength of the first heat exchange zone being less than the length of theprocess microchannel, the length of the second heat exchange zone beingless than the length of the first heat exchange zone.

FIG. 8 is a schematic illustration of a process microchannel that may beused with the inventive process, the process microchannel containing acatalyst having a flow-by configuration.

FIG. 9 is a schematic illustration of a process microchannel that may beused with the inventive process, the process microchannel containing acatalyst having a flow-through configuration.

FIG. 10 is a schematic illustration of a process microchannel that maybe used in the inventive process, the process microchannel containing afin assembly comprising a plurality of fins, a catalyst being supportedby the fins.

FIG. 11 illustrates an alternate embodiment of the process microchanneland fin assembly illustrated in FIG. 10.

FIG. 12 illustrates another alternate embodiment of the processmicrochannel and fin assembly illustrated in FIG. 10.

FIG. 13 is a plot of pore volume and surface area versus cobalt loadingobtained in Example 1.

FIGS. 14-17 are plots showing the results of the Fischer-Tropschsynthesis reactions conducted in Example 3.

FIG. 18 is a plot showing the differences in Fischer-Tropsch activityand selectivity for catalysts made in Example 4 with and withoutintercalcinations.

DETAILED DESCRIPTION OF THE INVENTION

The term “microchannel” refers to a channel having at least one internaldimension of height or width of up to about 10 millimeters (mm), and inone embodiment up to about 5 mm, and in one embodiment up to about 2 mm,and in one embodiment up to about 1 mm. The flow of fluid through themicrochannel may proceed along the length of the microchannel normal tothe height and width of the microchannel. An example of a microchannelthat may be used with the inventive process as a process microchanneland/or a heat exchange microchannel is illustrated in FIG. 1. Themicrochannel 10 illustrated in FIG. 1 has a height (h), width (w) andlength (l). Fluid flows through the microchannel 10 along the length ofthe microchannel in the direction indicated by arrows 12 and 14. Theheight (h) or width (w) of the microchannel may be in the range of about0.05 to about 10 mm, and in one embodiment about 0.05 to about 5 mm, andin one embodiment about 0.05 to about 2 mm, and in one embodiment about0.05 to about 1.5 mm, and in one embodiment about 0.05 to about 1 mm,and in one embodiment about 0.05 to about 0.75 mm, and in one embodimentabout 0.05 to about 0.5 mm. The other dimension of height or width maybe of any dimension, for example, up to about 3 meters, and in oneembodiment about 0.01 to about 3 meters, and in one embodiment about 0.1to about 3 meters. The length (l) of the microchannel may be of anydimension, for example, up to about 10 meters, and in one embodimentabout 0.2 to about 10 meters, and in one embodiment from about 0.2 toabout 6 meters, and in one embodiment from 0.2 to about 3 meters.Although the microchannel 10 illustrated in FIG. 1 has a cross sectionthat is rectangular, it is to be understood that the microchannel mayhave a cross section having any shape, for example, a square, circle,semi-circle, trapezoid, etc. The shape and/or size of the cross sectionof the microchannel may vary over its length. For example, the height orwidth may taper from a relatively large dimension to a relatively smalldimension, or vice versa, over the length of the microchannel.

The term “adjacent” when referring to the position of one channelrelative to the position of another channel means directly adjacent suchthat a wall separates the two channels. This wall may vary in thickness.However, “adjacent” channels are not separated by an intervening channelthat would interfere with heat transfer between the channels. In oneembodiment, one channel may be adjacent to another channel over onlypart of the dimension of the another channel. For example, a processmicrochannel may be longer than and extend beyond one or more adjacentheat exchange channels.

The term “fluid” refers to a gas, a liquid, or a gas or a liquidcontaining dispersed solids or liquid droplets.

The term “contact time” refers to the volume of the reaction zone withinthe microchannel reactor divided by the volumetric feed flow rate of thereactant composition at a temperature of 0° C. and a pressure of oneatmosphere.

The term “residence time” refers to the internal volume of a space(e.g., the reaction zone within a microchannel reactor) occupied by afluid flowing through the space divided by the average volumetricflowrate for the fluid flowing through the space at the temperature andpressure being used.

The term “reaction zone” refers to the space within the processmicrochannels wherein the reactants contact the catalyst.

The term “conversion of CO” refers to the CO mole change between thereactant composition and product divided by the moles of CO in thereactant composition.

The term “selectivity to methane” refers to the moles of methane in theproduct divided by the moles of methane plus two times the number ofmoles of C₂ hydrocarbons in the product, plus three times the number ofmoles of C₃ hydrocarbons in the product, plus four times the number ofmoles of C₄ hydrocarbons in the product, etc., until all of the moles ofhydrocarbons in the product have been included.

The term “one-pass conversion of CO” refers to the conversion of COafter one pass through the microchannel reactor employed with theinventive process.

The term “yield of product” refers to conversion of CO multiplied byselectivity to the indicated product(s).

The term “metal dispersion” refers to the percent of catalyticallyactive metal atoms and promoter atoms on the surface of the catalyst ascompared to the total number of metal atoms in the catalyst as measuredby hydrogen chemisorption which is described in “Heterogeneous Catalysisin Industrial Practice,” 2^(nd) ed., Charles N. Satterfield, p. 139,McGraw Hill (1996), which is incorporated herein by reference.

In the expression “about 0.5 gram of aliphatic hydrocarbon having atleast about 5 carbon atoms per gram of catalyst per hour” the weight ornumber of grams of catalyst refers to the total weight of the catalystconsisting of the catalytic metal (e.g., Co) or oxide thereof, optionalco-catalyst (e.g., Re or Ru), and/or promoter (e.g., Na, K, etc.) aswell as the weight of any support (e.g., alumina). However, if thecatalyst is supported on an engineered support structure such as a foam,felt, wad or fin, the weight of such engineered support structure is notincluded in the calculation of the weight or number of grams ofcatalyst. Similarly, if the catalyst is adhered to the microchannelwalls, the weight of the microchannel walls is not included in thecalculation.

The term “Co loading” refers to the weight of the Co in the catalystdivided by the total weight of the catalyst, that is, the total weightof the Co plus any co-catalyst or promoter as well as the support. Ifthe catalyst is supported on an engineered support structure such as afoam, felt, wad or fin, the weight of such engineered support structureis not included in the calculation. Similarly, if the catalyst isadhered to the microchannel walls, the weight of the microchannel wallsis not included in the calculation.

Referring to FIG. 2, the process may be conducted using microchannelreactor 100 which includes microchannel reactor core 102, reactantheader 104, product footer 106, heat exchange header 108 and heatexchange footer 110. The microchannel reactor core 102 contains aplurality of process microchannels and a plurality of heat exchangechannels adjacent to the process microchannels. The heat exchangechannels may be microchannels. The process microchannels and heatexchange channels may be aligned in layers, one above the other, or sideby side. A Fischer-Tropsch catalyst is contained within the processmicrochannels. The process header 104 provides a passageway for fluid toflow into the process microchannels with an even or substantially evendistribution of flow to the process microchannels. The process footer106 provides a passageway for fluid to flow from the processmicrochannels in a rapid manner with a relatively high rate of flow. Thereactant composition flows into the microchannel reactor 100 through thereactant header 104, as indicated by directional arrow 112. The reactantcomposition may be preheated prior to entering the reactant header 104.The reactant composition flows through the process microchannels in themicrochannel reactor core 102 in contact with the catalyst and reacts toform the desired product. In one embodiment, the flow of reactantcomposition and product through the reactor core 102 is in a verticaldirection, from the top of the reactor core 102 to its bottom. Theproduct, and in one embodiment unreacted components from the reactantcomposition, flow from the reactor core 102 through the product footer106, and out of product footer 106, as indicated by directional arrow114. Although an advantage of the inventive process is that a high levelof conversion of CO may be obtained with one pass through the processmicrochannels, in one embodiment, unreacted components from the reactantcomposition or a portion thereof may be recycled back through theprocess microchannels in contact with the catalyst. The unreactedcomponents of the reactant composition being recycled through theprocess microchannels may be recycled any number of times, for example,one, two, three, four times, etc. A heat exchange fluid flows into heatexchange header 108, as indicated by directional arrow 116, and fromheat exchange header 108 through the heat exchange channels inmicrochannel reactor core 102 to heat exchange footer 110, and out ofheat exchange footer 110, as indicated by directional arrow 118. Themicrochannel reactor 100 is employed in conjunction with storagevessels, pumps, valves, flow control devices, and the like, which arenot shown in the drawings, but would be apparent to those skilled in theart.

In one embodiment, the microchannel reactor core 102 may contain layersof process microchannels and heat exchange microchannels aligned side byside. An example of such microchannels layers is illustrated in FIG. 3.Referring to FIG. 3, process microchannel layers 130 and heat exchangemicrochannel layers 150 are stacked side by side to provide repeatingunit 170. Microchannel layer 130 provides for the flow of reactant andproduct. Microchannel layer 150 provides for the flow of heat exchangefluid.

Microchannel layer 130 contains a plurality of microchannels 132 alignedin parallel, each process microchannel 132 extending in a verticaldirection along the length of microchannel layer 130 from end 134 to end136, the process microchannels 132 extending along the width ofmicrochannel layer 130 from end 138 to end 140. Bonding strips 142 and144 are positioned at the ends 138 and 140, respectively, ofmicrochannel layer 130 to permit bonding of the microchannel layer 130to the next adjacent heat exchange layers 150. A catalyst is containedwithin the process microchannels 132. The flow of reactant and productthrough the process microchannels 132 may be in the direction indicatedby arrows 146 and 148. Each of the process microchannels 132 may have across section having any shape, for example, a square, rectangle,circle, semi-circle, etc. The internal height of each processmicrochannel 132 may be considered to be the vertical or horizontaldistance or gap between the microchannel layer 130 and the next adjacentheat exchange layer 150. Each process microchannel 132 may have aninternal height of up to about 10 mm, and in one embodiment up to about6 mm, and in one embodiment up to about 4 mm, and in one embodiment upto about 2 mm. In one embodiment, the height may be in the range ofabout 0.05 to about 10 mm, and in one embodiment about 0.05 to about 6mm, and in one embodiment about 0.05 to about 4 mm, and in oneembodiment about 0.05 to about 2 mm. The width of each of thesemicrochannels may be of any dimension, for example, up to about 3meters, and in one embodiment about 0.01 to about 3 meters, and in oneembodiment about 0.1 to about 3 meters. The length of each processmicrochannel 132 may be of any dimension, for example, up to about 10meters, and in one embodiment about 0.2 to about 10 meters, and in oneembodiment from about 0.2 to about 6 meters, and in one embodiment from0.2 to about 3 meters.

Microchannel layer 150 contains a plurality of heat exchangemicrochannels 152 aligned in parallel, each heat exchange microchannel152 extending horizontally along the width of microchannel layer 150from end 154 to end 156, the heat exchange microchannels 152 extendingalong the length of microchannel layer 150 from end 158 to end 160 ofmicrochannel layer 150. Bonding strips 162 and 164 are positioned atends 154 and 156, respectively, of microchannel layer 150 to permitbonding of the microchannel layer 150 to the next adjacent processmicrochannel layers 130. The heat exchange fluid may flow through theheat exchange microchannels 152 in the direction indicated by arrows 166and 168. The flow of heat exchange fluid in the direction indicated byarrows 166 and 168 is cross-current to the flow of reactant and productflowing through process microchannels 132 as indicated by arrows 146 and148. Alternatively, the heat exchange microchannels 152 could beoriented to provide for flow of the heat exchange fluid along the widthof the microchannel layer 150 from end 158 to end 160 or from end 160 toend 158. This would result in the flow of heat exchange fluid in adirection that would be cocurrent or counter-current to the flow ofreactant and product through the process microchannels 132. Each of theheat exchange microchannels 152 may have a cross section having anyshape, for example, a square, rectangle, circle, semi-circle, etc. Theinternal height of each heat exchange microchannel 152 may be consideredto be the vertical or horizontal distance or gap between the heatexchange microchannel layer 150 and the next adjacent microchannel layer130. Each of the heat exchange microchannels 152 may have an internalheight of up to about 2 mm, and in one embodiment in the range of about0.05 to about 2 mm, and in one embodiment about 0.05 to about 1.5 mm.The width of each of these microchannels may be of any dimension, forexample, up to about 3 meters, and in one embodiment from about 0.01 toabout 3 meters, and in one embodiment about 0.1 to about 3 meters. Thelength of each of the heat exchange microchannels 152 may be of anydimension, for example, up to about 10 meters, and in one embodimentfrom about 0.2 to about 10 meters, and in one embodiment from about 0.2to about 6 meters, and in one embodiment from 0.2 to about 3 meters.

Alternatively, the process microchannels and heat exchange microchannelsmay be aligned as provided for in repeating unit 170 a. Repeating unit170 a is illustrated in FIG. 4. Referring to FIG. 4, processmicrochannel 132 is positioned adjacent to microchannel layer 150 whichcontains heat exchange microchannels 152. A common wall 171 separatesthe process microchannel 132 from the heat exchange microchannel layer150. A catalyst 172 is packed into the process microchannel 132. Thereactant composition flows into and through the packed bed of catalyst172 in process microchannel 132 in the direction indicated bydirectional arrow 146, contacts catalyst 172 and reacts to form thedesired product. The product, and in one embodiment unreacted componentsfrom the reactant composition, exit the process microchannel 132 asindicated by directional arrow 148. Heat exchange fluid flows throughthe heat exchange microchannels 152 in a direction that is cross-currentto the flow of reactant composition and product through the processmicrochannel 132.

Alternatively, the process microchannels and heat exchange microchannelsmay be aligned as provided for in repeating unit 170 b. Repeating unit170 b illustrated in FIG. 5 is identical to the repeating unit 170 aillustrated in FIG. 4 with the exception that the microchannel layer 150is rotated 90° and the heat exchange fluid flowing through the heatexchange microchannel 152 flows in the direction indicated by directionarrows 166 a and 168 a which is countercurrent to the flow of reactantcomposition and product through the process microchannel 132.Alternatively, the heat exchange fluid could flow in the directionopposite to that indicated by directional arrows 166 a and 168 a andthereby provide for the flow of heat exchange fluid through the heatexchange microchannel 152 in a direction that would be cocurrentrelative to the direction of reactant composition and product throughthe process microchannel 132.

Alternatively, the process microchannels and heat exchange microchannelsmay be aligned as provided for in repeating unit 170 c. Repeating unit170 c is illustrated in FIG. 6. Referring to FIG. 6, processmicrochannel 132 a is positioned adjacent to heat exchange zone 151.Heat exchange zone 151 contains a plurality of heat exchangemicrochannels 152 aligned in parallel relative to one another, each heatexchange microchannel 152 extending lengthwise at a right angle relativeto the lengthwise direction of the process microchannel 132 a. Heatexchange zone 151 is shorter in length than process microchannel 132 a.Heat exchange zone 151 extends lengthwise from or near the entrance 134a to process microchannel 132 a to a point along the length of theprocess microchannel 132 a short of the exit 136 a to the processmicrochannel 132 a. In one embodiment, the length of heat exchange zone151 is up to about 100% of the length of process microchannel 132 a, andin one embodiment the length of heat exchange zone 151 is from about 5to about 100% of the length of the process microchannel 132 a, and inone embodiment the length of the heat exchange zone 151 is from about 5to about 50% of the length of the process microchannel 132 a, and in oneembodiment the length of the heat exchange zone 151 is from about 50% toabout 100% of the length of the process microchannel 132 a. The width ofthe process microchannel 132 a is expanded or extended in the areadownstream of the end 153 of the heat exchange zone 151. Thisarrangement provides the advantage of heat exchange (i.e., cooling) ator near the entrance 134 a to the process microchannel 132 a as well asto parts of the process microchannel 132 a downstream from the entrance.A catalyst 172 is packed in the process microchannel 132 a. The reactantcomposition flows into and through the packed bed of catalyst 172 inprocess microchannel 132 a in the direction indicated by directionalarrow 146, contacts catalyst 172 and reacts to form the desired product.The product, and in one embodiment unreacted components from thereactant composition, exit the process microchannel 132 a, as indicatedby directional arrow 148. Heat exchange fluid flows through the heatexchange microchannels 152 in a direction that is cross-current to theflow of reactant composition and product through the processmicrochannel 132 a.

Alternatively, the process microchannels and heat exchange microchannelsmay be aligned as provided for in repeating unit 170 d. Repeating unit170 d, which is illustrated in FIG. 7, is identical to the repeatingunit 170 c illustrated in FIG. 6 with the exception that repeating unit170 d includes heat exchange zone 151 a adjacent to process microchannel132 a on the opposite side of the process microchannel 132 a from theheat exchange zone 151. Heat exchange zone 151 a contains a plurality ofparallel heat exchange microchannels 152 a which are the same as orsimilar in size and design to the heat exchange microchannels 152discussed above. Heat exchange zone 151 a extends lengthwise from ornear the entrance 134 a to process microchannel 132 a to a point alongthe length of process microchannel 132 a short of the end 153 of heatexchange zone 151. The length of the heat exchange zone 151 a may beshorter than the length of the heat exchange zone 151. In oneembodiment, the length of the heat exchange zone 151 a may be up toabout 100% of the length of the process microchannel 132 a, and in oneembodiment the length of the heat exchange zone 151 a is from about 5 toabout 100% of the length of the process microchannel 132 a, and in oneembodiment the length of the heat exchange zone 151 a is from about 5 toabout 50% of the length of the process microchannel 132 a, and in oneembodiment the length of the heat exchange zone 151 a is from about 50%to about 100% of the length of the process microchannel 132 a. The widthof the process microchannel 132 a is expanded in the areas downstream ofthe ends 153 and 153 a of the heat exchange zones 151 and 151 a,respectively. This arrangement provides the advantage of heat exchange(i.e., cooling) at or near the entrance 134 a to the processmicrochannel 132 a as well to parts of the process microchannel 132 adownstream from the entrance 134 a. The use of the two heat exchangezones 151 and 151 a allows for a relatively high level of heat exchangein the area of the process microchannel 132 a near its entrance, and arelatively moderate heat exchange in the process microchannel downstreamfrom about the end 153 a of heat exchange zone 151 a. Catalyst 172 ispacked into the process microchannel 132 a. The reactant compositionflows into and through the packed bed of catalyst 172 in processmicrochannel 132 a in the direction indicated by directional arrow 146,contacts the catalyst 172 and reacts to form the desired product. Theproduct, and in one embodiment unreacted components from the reactantcomposition, exit the process microchannel 132 a, as indicated bydirectional arrow 148. Heat exchange fluid flows through the heatexchange channels 151 and 151 a in a direction which is cross-current tothe flow of reactant composition and product through the processmicrochannel 132 a.

The catalyst bed may be segregated into separate reaction zones in theprocess microchannels in the direction of flow through the processmicrochannels. In each reaction zone the length of one or more adjacentheat exchange zone(s) may vary in their dimensions. For example, in oneembodiment, the length of the one or more adjacent heat exchange zonesmay be less than about 50% of the length of each reaction zone.Alternatively, the one or more heat exchange zones may have lengths thatare more than about 50% of the length of each reaction zone up to about100% of the length of each reaction zone.

The number of microchannels in each of the microchannel layers 130 and150 may be any desired number, for example, one, two, three, four, five,six, eight, ten, hundreds, thousands, tens of thousands, hundreds ofthousands, millions, etc. Similarly, the number of repeating units 170(or 170 a through 170 d) of microchannel layers in the microchannelreactor core 102 may be any desired number, for example, one, two,three, four, six, eight, ten, hundreds, thousands, etc.

The microchannel reactor 100, including the microchannel reactor core102, may be constructed of any material that provides sufficientstrength, dimensional stability and heat transfer characteristics forcarrying out the inventive process. Examples of suitable materialsinclude steel (e.g., stainless steel, carbon steel, and the like),aluminum, titanium, nickel, and alloys of any of the foregoing metals,plastics (e.g., epoxy resins, UV cured resins, thermosetting resins, andthe like), monel, inconel, ceramics, glass, composites, quartz, silicon,or a combination of two or more thereof. The microchannel reactor may befabricated using known techniques including wire electrodischargemachining, conventional machining, laser cutting, photochemicalmachining, electrochemical machining, molding, water jet, stamping,etching (for example, chemical, photochemical or plasma etching) andcombinations thereof. The microchannel reactor may be constructed byforming layers or sheets with portions removed that allow flow passage.A stack of sheets may be assembled via diffusion bonding, laser welding,diffusion brazing, and similar methods to form an integrated device. Themicrochannel reactor has appropriate manifolds, valves, conduit lines,etc. to control flow of the reactant composition and product, and flowof the heat exchange fluid. These are not shown in the drawings, but canbe readily provided by those skilled in the art.

The reactant composition comprises a mixture of H₂ and CO. This mixturemay be referred to as synthesis gas or syngas. The molar ratio of H₂ toCO may range from about 0.8 to about 10, and in one embodiment about 0.8to about 5, and in one embodiment about 1 to about 3, and in oneembodiment about 1.5 to about 3, and in one embodiment about 1.8 toabout 2.5, and in one embodiment about 1.9 to about 2.2, and in oneembodiment about 2.05 to about 2.10. The reactant composition may alsocontain CO₂ and/or H₂O, as well as light hydrocarbons of 1 to about 4carbon atoms, and in one embodiment 1 to about 2 carbon atoms. Thereactant composition may contain from about 5 to about 45% by volume CO,and in one embodiment about 5 to about 20% by volume CO; and about 55 toabout 95% by volume H₂, and in one embodiment about 80 to about 95% byvolume H₂. The concentration of CO₂ in the reactant composition may beup to about 60% by volume, and in one embodiment about 5 to about 60% byvolume, and in one embodiment about 5 to about 40% by volume. Theconcentration of H₂O in the reactant composition may be up to about 80%by volume, and in one embodiment about 5 to about 80% by volume, and inone embodiment about 5 to about 50% by volume. The concentration oflight hydrocarbons in the reactant composition may be up to about 80% byvolume, and in one embodiment about 1 to about 80% by volume, and in oneembodiment about 1 to about 50% by volume. The reactant composition maycomprise recycled gaseous products formed during the inventive process.The reactant composition may comprise a stream (e.g., a gaseous stream)from another process such as a steam reforming process (product streamwith H₂/CO mole ratio of about 3), a partial oxidation process (productstream with H₂/CO mole ration of about 2), an autothermal reformingprocess (product stream with H₂/CO mole ratio of about 2.5), a CO₂reforming process (product stream with H₂/CO mole ratio of about 1), acoal gassification process (product stream with H₂/CO mole ratio ofabout 1), and combinations thereof.

The presence of contaminants such as sulfur, nitrogen, halogen,selenium, phosphorus, arsenic, and the like, in the reactant compositionmay be undesirable. Thus, in one embodiment of the invention, theforegoing contaminants may be removed from the reactant composition orhave their concentrations reduced prior to conducting the inventiveprocess. Techniques for removing these contaminants are well known tothose of skill in the art. For example, ZnO guardbeds may be used forremoving sulfur impurities. In one embodiment, the contaminant level inthe reactant composition may be at a level of up to about 5% by volume,and in one embodiment up to about 1% by volume, and in one embodiment upto about 0.1% by volume, and in one embodiment up to about 0.05% byvolume.

The heat exchange fluid may be any fluid. These include air, steam,liquid water, gaseous nitrogen, other gases including inert gases,carbon monoxide, molten salt, oils such as mineral oil, and heatexchange fluids such as Dowtherm A and Therminol which are availablefrom Dow-Union Carbide.

The heat exchange fluid may comprise a stream of the reactantcomposition. This can provide process pre-heat and increase in overallthermal efficiency of the process.

In one embodiment, the heat exchange channels comprise process channelswherein an endothermic process is conducted. These heat exchange processchannels may be microchannels. Examples of endothermic processes thatmay be conducted in the heat exchange channels include steam reformingand dehydrogenation reactions. Steam reforming of an alcohol that occursat a temperature in the range of about 200° C. to about 300° C. isanother example of such an endothermic process. The incorporation of asimultaneous endothermic reaction to provide an improved heat sink mayenable a typical heat flux of roughly an order of magnitude above theconvective cooling heat flux. The use of simultaneous exothermic andendothermic reactions to exchange heat in a microchannel reactor isdisclosed in U.S. patent application Ser. No. 10/222,196, filed Aug. 15,2002, which is incorporated herein by reference.

In one embodiment, the heat exchange fluid undergoes a partial or fullphase change as it flows through the heat exchange channels. This phasechange provides additional heat removal from the process microchannelsbeyond that provided by convective cooling. For a liquid heat exchangefluid being vaporized, the additional heat being transferred from theprocess microchannels would result from the latent heat of vaporizationrequired by the heat exchange fluid. An example of such a phase changewould be an oil or water that undergoes boiling. In one embodiment,about 50% by weight of the heat exchange fluid is vaporized.

The heat flux for convective heat exchange in the microchannel reactormay range from about 1 to about 25 watts per square centimeter ofsurface area of the process microchannels (W/cm²) in the microchannelreactor, and in one embodiment from about 1 to about 10 W/cm². The heatflux for phase change or simultaneous endothermic reaction heat exchangemay range from about 1 to about 250 W/cm², and in one embodiment fromabout 1 to about 100 W/cm², and in one embodiment from about 1 to about50 W/cm², and in one embodiment from about 1 to about 25 W/cm², and inone embodiment from about 1 to about 10 W/cm².

The cooling of the process microchannels during the inventive process,in one embodiment, is advantageous for controlling selectivity towardsthe main or desired product due to the fact that such added coolingreduces or eliminates the formation of undesired by-products fromundesired parallel reactions with higher activation energies. As aresult of this cooling, in one embodiment, the temperature of thereactant composition at the entrance to the process microchannels may bewithin about 200° C., and in one embodiment within about 150° C., and inone embodiment within about 100° C., and in one embodiment within about50° C., and in one embodiment within about 25° C., and in one embodimentwithin about 10° C., of the temperature of the product (or mixture ofproduct and unreacted reactants) at the exit of the processmicrochannels.

The catalyst may comprise any Fischer-Tropsch catalyst. The catalystcomprises at least one catalytically active metal or oxide thereof. Inone embodiment, the catalyst further comprises a catalyst support. Inone embodiment, the catalyst further comprises at least one promoter.The catalytically active metal may comprise Co, Fe, Ni, Ru, Re, Os, or acombination of two or more thereof. The support material may comprisealumina, zirconia, silica, aluminum fluoride, fluorided alumina,bentonite, ceria, zinc oxide, silica-alumina, silicon carbide, amolecular sieve, or a combination of two or more thereof. The supportmaterial may comprise a refractory oxide. The promoter may comprise aGroup IA, IIA, IIIB or IVB metal or oxide thereof, a lanthanide metal ormetal oxide, or an actinide metal or metal oxide. In one embodiment, thepromoter is Li, B, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Sc, Y, La, Ac, Ti, Zr,La, Ac, Ce or Th, or an oxide thereof, or a mixture of two or morethereof. Examples of catalysts that may be used include those disclosedin U.S. Pat. Nos. 4,585,798; 5,036,032; 5,733,839; 6,075,062; 6,136,868;6,262,131B1; 6,353,035B2; 6,368,997B2; 6,476,085B2; 6,451,864B1;6,490,880B1; 6,537,945B2; 6,558,634B1; and U.S. Patent Publications2002/0028853A1; 2002/0188031A1; and 2003/0105171A1; these patents andpatent publications being incorporated herein by reference for theirdisclosures of Fischer-Tropsch catalysts and methods for preparing suchcatalysts.

In one embodiment, the catalyst comprises Co, and optionally aco-catalyst and/or promoter, supported on a support wherein the Coloading is at least about 5% by weight, and in one embodiment at leastabout 10% by weight, and in one embodiment at least about 15% by weight,and in one embodiment at least about 20% by weight, and in oneembodiment at least about 25% by weight, and in one embodiment at leastabout 28% by weight, and in one embodiment at least about 30% by weight,and in one embodiment at least about 32% by weight, and in oneembodiment at least about 35% by weight, and in one embodiment at leastabout 40% by weight. In one embodiment, the Co loading may be from about5 to about 50% by weight, and in one embodiment about 10 to about 50% byweight, and in one embodiment about 15 to about 50% by weight, and inone embodiment about 20 to about 50% by weight, and in one embodimentabout 25 to about 50% by weight, and in one embodiment about 28 to about50% by weight, and in one embodiment about 30 to about 50% by weight,and in one embodiment about 32 to about 50% by weight. The metaldispersion for the catalytically active metal (i.e., Co, and optionallyco-catalyst and/or promoter) of the catalyst may range from about 1 toabout 30%, and in one embodiment about 2 to about 20%, and in oneembodiment about 3 to about 20%. The co-catalyst may be Fe, Ni, Ru, Re,Os, or an oxide thereof, or a mixture of two or more thereof. Thepromoter may be a Group IA, IIA, IIIB or IVB metal or oxide thereof, alanthanide metal or metal oxide, or an actinide metal or metal oxide. Inone embodiment, the promoter is Li, B, Na, K, Rb, Cs, Mg, Ca, Sr, Ba,Sc, Y, La, Ac, Ti, Zr, La, Ac, Ce or Th, or an oxide thereof, or amixture of two or more thereof. The co-catalyst may be employed at aconcentration of up to about 10% by weight based on the total weight ofthe catalyst (i.e., the weight of catalyst, co-catalyst, promoter andsupport), and in one embodiment about 0.1 to about 5% by weight. Thepromoter may be employed at a concentration of up to about 10% by weightbased on the total weight of the catalyst, and in one embodiment about0.1 to about 5% by weight.

In one embodiment, the catalyst may comprise Co supported by alumina;the loading of Co being at least about 25% by weight, and in oneembodiment at least about 28% by weight, and in one embodiment at leastabout 30% by weight, and in one embodiment at least about 32% by weight;and the Co dispersion is at least about 3%, and in one embodiment atleast about 5%, and in one embodiment at least about 7%.

In one embodiment, the catalyst may comprise a composition representedby the formula

CoM¹ _(a)M² _(b)O_(x)

wherein: M¹ is Fe, Ni, Ru, Re, Os or a mixture thereof, and in oneembodiment M¹ is Ru or Re or a mixture thereof; M² is Li, B, Na, K, Rb,Cs, Mg, Ca, Sr, Ba, Sc, Y, La, Ac, Ti, Zr, La, Ac, Ce or Th, or amixture of two or more thereof; a is a number in the range of zero toabout 0.5, and in one embodiment zero to about 0.2; b is a number in therange of zero to about 0.5, and in one embodiment zero to about 0.1; andx is the number of oxygens needed to fulfill the valency requirements ofthe elements present.

In one embodiment, the catalyst used in the inventive process may bemade using multiple impregnation steps wherein intercalcination stepsare conducted between each impregnation step. The use of such aprocedure, at least in one embodiment, allows for the formation ofcatalysts with levels of loading of catalytic metal and optionallypromoter that are higher than with procedures wherein suchintercalcination steps are not employed. In one embodiment, a catalyticmetal (e.g., Co) and optionally co-catalyst (e.g., Re or Ru) and/orpromoter is loaded on a support (e.g., Al₂O₃) using the followingsequence of steps: (A) impregnating the support with a compositioncomprising a catalytic metal and optionally a co-catalyst and/orpromoter to provide an intermediate catalytic product; (B) calcining theintermediate catalytic product formed in step (A); (C) impregnating thecalcined intermediate product formed in (B) with another compositioncomprising a catalytic metal and optionally a co-catalyst and/orpromoter, to provide another intermediate catalytic product; and (D)calcining the another intermediate catalytic product formed in step (C)to provide the desired catalyst product. The catalytic metal andoptional co-catalyst and/or promoter may be impregnated on the supportusing an incipient wetness impregnation process. Steps (C) and (D) maybe repeated one or more additional times until the desired loading ofcatalytic metal, and optional co-catalyst and/or promoter, is achieved.The composition comprising the catalytic metal may be a nitrate solutionof the metal, for example, a cobalt nitrate solution. The process may becontinued until the catalytic metal (i.e., Co) achieves a loading levelof about 20% by weight or more, and in one embodiment about 25% byweight or more, and in one embodiment about 28% by weight or more, andin one embodiment about 30% by weight or more, and in one embodimentabout 32% by weight or more, and in one embodiment about 35% by weightor more, and in one embodiment about 37% by weight or more, and in oneembodiment about 40% by weight or more. Each of the calcination stepsmay comprise heating the catalyst at a temperature in the range of about100° C. to about 500° C., and in one embodiment about 100° C. to about400° C., and in one embodiment about 250 to about 350° C. for about 0.5to about 100 hours, and in one embodiment about 0.5 to about 24 hours,and in one embodiment about 2 to about 3 hours. The temperature may beramped to the calcination temperature at a rate of about 1-20° C./min.The calcination steps may be preceded by drying steps wherein thecatalyst is dried at a temperature of about 75 to about 200° C., and inone embodiment about 75° C. to about 150° C., for about 0.5 to about 100hours, and in one embodiment about 0.5 to about 24 hours. In oneembodiment, the catalyst may be dried for about 12 hours at about 90° C.and then at about 110-120° C. for about 1-1.5 hours, the temperaturebeing ramped from 90° C. to 110-120° C. at a rate of about 0.5-1°C./min.

The catalyst used in a microchannel reactor may have any size andgeometric configuration that fits within the process microchannels. Thecatalyst may be in the form of particulate solids (e.g., pellets,powder, fibers, and the like) having a median particle diameter of about1 to about 1000 μm (microns), and in one embodiment about 10 to about500 μm, and in one embodiment about 25 to about 250 μm. In oneembodiment, the catalyst is in the form of a fixed bed of particulatesolids.

In one embodiment, the catalyst is in the form of a fixed bed ofparticulate solids, the median particle diameter of the catalystparticulate solids is relatively small, and the length of each processmicrochannel is relatively short. The median particle diameter may be inthe range of about 1 to about 1000 μm, and in one embodiment about 10 toabout 500 μm, and the length of each process microchannel may be in therange of up to about 500 cm, and in one embodiment about 10 to about 500cm, and in one embodiment about 50 to about 300 cm.

The catalyst may be supported on a porous support structure such as afoam, felt, wad or a combination thereof. The term “foam” is used hereinto refer to a structure with continuous walls defining pores throughoutthe structure. The term “felt” is used herein to refer to a structure offibers with interstitial spaces therebetween. The term “wad” is usedherein to refer to a structure of tangled strands, like steel wool. Thecatalyst may be supported on a honeycomb structure.

The catalyst may be supported on a flow-by support structure such as afelt with an adjacent gap, a foam with an adjacent gap, a fin structurewith gaps, a washcoat on any inserted substrate, or a gauze that isparallel to the flow direction with a corresponding gap for flow. Anexample of a flow-by structure is illustrated in FIG. 8. In FIG. 8, thecatalyst 300 is contained within process microchannel 302. An openpassage way 304 permits the flow of fluid through the processmicrochannel 302 in contact with the catalyst 300 as indicated by arrows306 and 308.

The catalyst may be supported on a flow-through support structure suchas a foam, wad, pellet, powder, or gauze. An example of a flow-throughstructure is illustrated in FIG. 9. In FIG. 9, the flow-through catalyst310 is contained within process microchannel 312 and the fluid flowsthrough the catalyst 310 as indicated by arrows 314 and 316.

The support structure for a flow-through catalyst may be formed from amaterial comprising silica gel, foamed copper, sintered stainless steelfiber, steel wool, alumina, poly(methyl methacrylate), polysulfonate,poly(tetrafluoroethylene), iron, nickel sponge, nylon, polyvinylidenedifluoride, polypropylene, polyethylene, polyethylene ethylketone,polyvinyl alcohol, polyvinyl acetate, polyacrylate,polymethylmethacrylate, polystyrene, polyphenylene sulfide, polysulfone,polybutylene, or a combination of two or more thereof. In oneembodiment, the support structure may be made of a heat conductingmaterial, such as a metal, to enhance the transfer of heat away from thecatalyst.

The catalyst may be directly washcoated on the interior walls of theprocess microchannels, grown on the walls from solution, or coated insitu on a fin structure. The catalyst may be in the form of a singlepiece of porous contiguous material, or many pieces in physical contact.In one embodiment, the catalyst may be comprised of a contiguousmaterial and has a contiguous porosity such that molecules can diffusethrough the catalyst. In this embodiment, the fluids flow through thecatalyst rather than around it. In one embodiment, the cross-sectionalarea of the catalyst occupies about 1 to about 99%, and in oneembodiment about 10 to about 95% of the cross-sectional area of theprocess microchannels. The catalyst may have a surface area, as measuredby BET, of greater than about 0.5 m²/g, and in one embodiment greaterthan about 2 m²/g.

The catalyst may comprise a porous support, an interfacial layer on theporous support, and a catalyst material on the interfacial layer. Theinterfacial layer may be solution deposited on the support or it may bedeposited by chemical vapor deposition or physical vapor deposition. Inone embodiment the catalyst has a porous support, a buffer layer, aninterfacial layer, and a catalyst material. Any of the foregoing layersmay be continuous or discontinuous as in the form of spots or dots, orin the form of a layer with gaps or holes.

The porous support may have a porosity of at least about 5% as measuredby mercury porosimetry and an average pore size (sum of pore diametersdivided by number of pores) of about 1 to about 1000 μm. The poroussupport may be a porous ceramic or a metal foam. Other porous supportsthat may be used include carbides, nitrides, and composite materials.The porous support may have a porosity of about 30% to about 99%, and inone embodiment about 60% to about 98%. The porous support may be in theform of a foam, felt, wad, or a combination thereof. The open cells ofthe metal foam may range from about 20 pores per inch (ppi) to about3000 ppi, and in one embodiment about 20 to about 1000 ppi, and in oneembodiment about 40 to about 120 ppi. The term “ppi” refers to thelargest number of pores per inch (in isotropic materials the directionof the measurement is irrelevant; however, in anisotropic materials, themeasurement is done in the direction that maximizes pore number).

The buffer layer, when present, may have a different composition and/ordensity than both the porous support and the interfacial layers, and inone embodiment has a coefficient of thermal expansion that isintermediate the thermal expansion coefficients of the porous supportand the interfacial layer. The buffer layer may be a metal oxide ormetal carbide. The buffer layer may be comprised of Al₂O₃, TiO₂, SiO₂,ZrO₂, or combination thereof. The Al₂O₃ may be α-Al₂O₃, γ-Al₂O₃ or acombination thereof. α-Al₂O₃ provides the advantage of excellentresistance to oxygen diffusion. The buffer layer may be formed of two ormore compositionally different sublayers. For example, when the poroussupport is metal, for example a stainless steel foam, a buffer layerformed of two compositionally different sub-layers may be used. Thefirst sublayer (in contact with the porous support) may be TiO₂. Thesecond sublayer may be α-Al₂O₃ which is placed upon the TiO₂. In oneembodiment, the α-Al₂O₃ sublayer is a dense layer that providesprotection of the underlying metal surface. A less dense, high surfacearea interfacial layer such as alumina may then be deposited as supportfor a catalytically active layer.

The porous support may have a thermal coefficient of expansion differentfrom that of the interfacial layer. In such a case a buffer layer may beneeded to transition between the two coefficients of thermal expansion.The thermal expansion coefficient of the buffer layer can be tailored bycontrolling its composition to obtain an expansion coefficient that iscompatible with the expansion coefficients of the porous support andinterfacial layers. The buffer layer should be free of openings and pinholes to provide superior protection of the underlying support. Thebuffer layer may be nonporous. The buffer layer may have a thicknessthat is less than one half of the average pore size of the poroussupport. The buffer layer may have a thickness of about 0.05 to about 10μm, and in one embodiment about 0.05 to about 5 μm.

In one embodiment of the invention, adequate adhesion and chemicalstability may be obtained without a buffer layer. In this embodiment thebuffer layer may be omitted.

The interfacial layer may comprise nitrides, carbides, sulfides,halides, metal oxides, carbon, or a combination thereof. The interfaciallayer provides high surface area and/or provides a desirablecatalyst-support interaction for supported catalysts. The interfaciallayer may be comprised of any material that is conventionally used as acatalyst support. The interfacial layer may be comprised of a metaloxide. Examples of metal oxides that may be used include γ-Al₂O₃, SiO₂,ZrO₂, TiO₂, tungsten oxide, magnesium oxide, vanadium oxide, chromiumoxide, manganese oxide, iron oxide, nickel oxide, cobalt oxide, copperoxide, zinc oxide, molybdenum oxide, tin oxide, calcium oxide, aluminumoxide, lanthanum series oxide(s), zeolite(s) and combinations thereof.The interfacial layer may serve as a catalytically active layer withoutany further catalytically active material deposited thereon. Usually,however, the interfacial layer is used in combination with acatalytically active layer. The interfacial layer may also be formed oftwo or more compositionally different sublayers. The interfacial layermay have a thickness that is less than one half of the average pore sizeof the porous support. The interfacial layer thickness may range fromabout 0.5 to about 100 μm, and in one embodiment from about 1 to about50 μm. The interfacial layer may be either crystalline or amorphous. Theinterfacial layer may have a BET surface area of at least about 1 m²/g.

The catalyst may be deposited on the interfacial layer. Alternatively,the catalyst material may be simultaneously deposited with theinterfacial layer. The catalyst layer may be intimately dispersed on theinterfacial layer. That the catalyst layer is “dispersed on” or“deposited on” the interfacial layer includes the conventionalunderstanding that microscopic catalyst particles are dispersed: on thesupport layer (i.e., interfacial layer) surface, in crevices in thesupport layer, and in open pores in the support layer.

The catalyst may be supported on an assembly of one or more finspositioned within the process microchannels. Examples are illustrated inFIGS. 10-12. Referring to FIG. 10, fin assembly 320 includes fins 322which are mounted on fin support 324 which overlies base wall 326 ofprocess microchannel 328. The fins 322 project from the fin support 324into the interior of the process microchannel 328. The fins 322 extendto and may contact the interior surface of upper wall 330 of processmicrochannel 328. Fin channels 332 between the fins 322 provide passageways for fluid to flow through the process microchannel 328 parallel toits length. Each of the fins 322 has an exterior surface on each of itssides, this exterior surface provides a support base for the catalyst.With the inventive process, the reactant composition flows through thefin channels 332, contacts the catalyst supported on the exteriorsurface of the fins 322, and reacts to form the product. The finassembly 320 a illustrated in FIG. 11 is similar to the fin assembly 320illustrated in FIG. 10 except that the fins 322 a do not extend all theway to the interior surface of the upper wall 330 of the microchannel328. The fin assembly 320 b illustrated in FIG. 12 is similar to the finassembly 320 illustrated in FIG. 10 except that the fins 322 b in thefin assembly 320 b have cross sectional shapes in the form oftrapezoids. Each of the fins may have a height ranging from about 0.02mm up to the height of the process microchannel 328, and in oneembodiment from about 0.02 to about 10 mm, and in one embodiment fromabout 0.02 to about 5 mm, and in one embodiment from about 0.02 to about2 mm. The width of each fin may range from about 0.02 to about 5 mm, andin one embodiment from about 0.02 to about 2 mm and in one embodimentabout 0.02 to about 1 mm. The length of each fin may be of any length upto the length of the process microchannel 328, and in one embodiment upto about 10 m, and in one embodiment about 0.5 to about 10 m, and in oneembodiment about 0.5 to about 6 m, and in one embodiment about 0.5 toabout 3 m. The gap between each of the fins may be of any value and mayrange from about 0.02 to about 5 mm, and in one embodiment from about0.02 to about 2 mm, and in one embodiment from about 0.02 to about 1 mm.The number of fins in the process microchannel 328 may range from about1 to about 50 fins per centimeter of width of the process microchannel328, and in one embodiment from about 1 to about 30 fins per centimeter,and in one embodiment from about 1 to about 10 fins per centimeter, andin one embodiment from about 1 to about 5 fins per centimeter, and inone embodiment from about 1 to about 3 fins per centimeter. Each of thefins may have a cross-section in the form of a rectangle or square asillustrated in FIG. 10 or 11, or a trapezoid as illustrated in FIG. 12.When viewed along its length, each fin may be straight, tapered or havea serpentine configuration. The fin assembly may be made of any materialthat provides sufficient strength, dimensional stability and heattransfer characteristics to permit operation for which the processmicrochannel is intended. These materials include: steel (e.g.,stainless steel, carbon steel, and the like); monel; inconel; aluminum;titanium; nickel; platinum; rhodium; copper; chromium; brass; alloys ofany of the foregoing metals; polymers (e.g., thermoset resins);ceramics; glass; composites comprising one or more polymers (e.g.,thermoset resins) and fiberglass; quartz; silicon; or a combination oftwo or more thereof. The fin assembly may be made of an Al₂O₃ formingmaterial such as an alloy comprising Fe, Cr, Al and Y, or a Cr₂O₃forming material such as an alloy of Ni, Cr and Fe.

In one embodiment, the catalyst may be regenerated. This may be done byflowing a regenerating fluid through the process microchannels incontact with the catalyst. The regenerating fluid may comprise hydrogenor a diluted hydrogen stream. The diluent may comprise nitrogen, argon,helium, methane, carbon dioxide, steam, or a mixture of two or morethereof. The regenerating fluid may flow from the header 104 through theprocess microchannels and to the footer 106, or in the oppositedirection from the footer 106 through the process microchannels to theheader 104. The temperature of the regenerating fluid may be from about50 to about 400° C., and in one embodiment about 200 to about 350° C.The pressure within the process microchannels during this regenerationstep may range from about 1 to about 40 atmospheres, and in oneembodiment about 1 to about 20 atmospheres, and in one embodiment about1 to about 5 atmospheres. The residence time for the regenerating fluidin the process microchannels may range from about 0.01 to about 1000seconds, and in one embodiment about 0.1 second to about 100 seconds.

In one embodiment, the process microchannels may be characterized byhaving a bulk flow path. The term “bulk flow path” refers to an openpath (contiguous bulk flow region) within the process microchannels. Acontiguous bulk flow region allows rapid fluid flow through themicrochannels without large pressure drops. In one embodiment, the flowof fluid in the bulk flow region is laminar. Bulk flow regions withineach process microchannel may have a cross-sectional area of about 0.05to about 10,000 mm², and in one embodiment about 0.05 to about 5000 mm²,and in one embodiment about 0.1 to about 2500 mm². The bulk flow regionsmay comprise from about 5% to about 95%, and in one embodiment about 30%to about 80% of the cross-section of the process microchannels.

The contact time of the reactants with the catalyst within the processmicrochannels may range up to about 2000 milliseconds (ms), and in oneembodiment from about 10 ms to about 1000 ms, and in one embodimentabout 20 ms to about 500 ms. In one embodiment, the contact time mayrange up to about 300 ms, and in one embodiment from about 20 to about300 ms, and in one embodiment from about 50 to about 150 ms, and in oneembodiment about 75 to about 125 ms, and in one embodiment about 100 ms.

The space velocity (or gas hourly space velocity (GHSV)) for the flow ofthe reactant composition and product through the process microchannelsmay be at least about 1000 hr⁻¹ (normal liters of feed/hour/liter ofvolume within the process microchannels) or at least about 800 mlfeed/(g catalyst) (hr). The space velocity may range from about 1000 toabout 1,000,000 hr⁻¹, or from about 800 to about 800,000 ml feed/(gcatalyst) (hr). In one embodiment, the space velocity may range fromabout 10,000 to about 100,000 hr⁻¹, or about 8,000 to about 80,000 mlfeed/(g catalyst) (hr).

The temperature of the reactant composition entering the processmicrochannels may range from about 150° C. to about 270° C., and in oneembodiment about 180° C. to about 250° C., and in one embodiment about180° C. to about 220° C.

The temperature of the reactant composition and product within theprocess microchannels may range from about 200° C. to about 300° C., andin one embodiment from about 220° C. to about 270° C., and in oneembodiment from about 220° C. to about 250° C.

The temperature of the product exiting the process microchannels mayrange from about 200° C. to about 300° C., and in one embodiment about220° C. to about 270° C., and in one embodiment about 220° C. to about250° C.

The pressure within the process microchannels may be at least about 5atmospheres, and in one embodiment at least about 10 atmospheres, and inone embodiment at least about 15 atmospheres, and in one embodiment atleast about 20 atmospheres, and in one embodiment at least about 25atmospheres, and in one embodiment at least about 30 atmospheres. In oneembodiment the pressure may range from about 5 to about 50 atmospheres,and in one embodiment from about 10 to about 50 atmospheres, and in oneembodiment from about 10 to about 30 atmospheres, and in one embodimentfrom about 10 to about 25 atmospheres, and in one embodiment from about15 to about 25 atmospheres.

The pressure drop of the reactants and/or products as they flow throughthe process microchannels may range up to about 10 atmospheres per meterof length of the process microchannel (atm/m), and in one embodiment upto about 5 atm/m, and in one embodiment up to about 3 atm/m.

The reactant composition entering the process microchannels is typicallyin the form of a vapor, while the product exiting the processmicrochannels may be in the form of a vapor, a liquid, or a mixture ofvapor and liquid. The Reynolds Number for the flow of vapor through theprocess microchannels may be in the range of about 10 to about 4000, andin one embodiment about 100 to about 2000. The Reynolds Number for theflow of liquid through the process microchannels may be about 10 toabout 4000, and in one embodiment about 100 to about 2000.

The heat exchange fluid entering the heat exchange channels may be at atemperature of about 150° C. to about 300° C., and in one embodimentabout 150° C. to about 270° C. The heat exchange fluid exiting the heatexchange channels may be at a temperature in the range of about 220° C.to about 270° C., and in one embodiment about 230° C. to about 250° C.The residence time of the heat exchange fluid in the heat exchangechannels may range from about 50 to about 5000 ms, and in one embodimentabout 100 to about 1000 ms. The pressure drop for the heat exchangefluid as it flows through the heat exchange channels may range up toabout 10 atm/m, and in one embodiment from about 1 to about 10 atm/m,and in one embodiment from about 2 to about 5 atm/m. The heat exchangefluid may be in the form of a vapor, a liquid, or a mixture of vapor andliquid. The Reynolds Number for the flow of vapor through the heatexchange channels may be from about 10 to about 4000, and in oneembodiment about 100 to about 2000. The Reynolds Number for the flow ofliquid through heat exchange channels may be from about 10 to about4000, and in one embodiment about 100 to about 2000.

The conversion of CO may be about 40% or higher per cycle, and in oneembodiment about 50% or higher, and in one embodiment about 55% orhigher, and in one embodiment about 60% or higher, and in one embodimentabout 65% or higher, and in one embodiment about 70% or higher. The term“cycle” is used herein to refer to a single pass of the reactantsthrough the process microchannels.

The selectivity to methane in the product may be about 25% or less, andin one embodiment about 20% or less, and in one embodiment about 15% orless, and in one embodiment about 12% or less, and in one embodimentabout 10% or less.

The yield of product may be about 25% or higher per cycle, and in oneembodiment about 30% or higher, and in one embodiment about 40% orhigher per cycle.

In one embodiment, the conversion of CO is at least about 50%, theselectivity to methane is about 15% or less, and the yield of product isat least about 35% per cycle.

The product formed by the inventive process may comprise a gaseousproduct fraction and a liquid product fraction. The gaseous productfraction may include hydrocarbons boiling below about 350° C. atatmospheric pressure (e.g., tail gases through middle distillates). Theliquid product fraction (the condensate fraction) may includehydrocarbons boiling above about 350° C. (e.g., vacuum gas oil throughheavy paraffins).

The product fraction boiling below about 350° C. may be separated into atail gas fraction and a condensate fraction, e.g., normal paraffins ofabout 5 to about 20 carbon atoms and higher boiling hydrocarbons, using,for example, a high pressure and/or lower temperature vapor-liquidseparator, or low pressure separators or a combination of separators.The fraction boiling above about 350° C. (the condensate fraction) maybe separated into a wax fraction boiling in the range of about 350° C.to about 650° C. after removing one or more fractions boiling aboveabout 650° C. The wax fraction may contain linear paraffins of about 20to about 50 carbon atoms with relatively small amounts of higher boilingbranched paraffins. The separation may be effected using fractionaldistillation.

The product formed by the inventive process may include methane, wax andother heavy high molecular weight products. The product may includeolefins such as ethylene, normal and iso-paraffins, and combinationsthereof. These may include hydrocarbons in the distillate fuel ranges,including the jet or diesel fuel ranges.

Branching may be advantageous in a number of end-uses, particularly whenincreased octane values and/or decreased pour points are desired. Thedegree of isomerization may be greater than about 1 mole of isoparaffinper mole of n-paraffin, and in one embodiment about 3 moles ofisoparaffin per mole of n-paraffin. When used in a diesel fuelcomposition, the product may comprise a hydrocarbon mixture having acetane number of at least about 60.

Commercially, higher molecular weight products, for example waxes, mayeither be isolated and used directly, or reacted to form lower molecularweight products. For example, high molecular weight products may behydrocracked to provide lower molecular weight products, increasing theyield of liquid combustible fuels. Hydrocracking refers to a catalyticprocess, usually carried out in the presence of free hydrogen, in whichthe cracking of the larger hydrocarbon molecules is a primary purpose ofthe operation. Catalysts used in carrying out hydrocracking operationsare well known in the art; see, for example, U.S. Pat. Nos. 4,347,121and 4,810,357, which are incorporated herein by reference, for theirdescriptions of hydrotreating, hydrocracking, and catalysts used in eachprocess. The product formed by the inventive process may be furtherprocessed to form a lubricating base oil or diesel fuel. For example,the product made by the inventive process may be hydrocracked and thensubjected to distillation and/or catalytic isomerization to provide alubricating base oil, diesel fuel, and the like.

The hydrocarbon products made by the inventive process may behydroisomerized using the process disclosed in U.S. Pat. Nos. 6,103,099or 6,180,575; hydrocracked and hydroisomerized using the processdisclosed in U.S. Pat. No. 4,943,672 or 6,096,940; dewaxed using theprocess disclosed in U.S. Pat. No. 5,882,505; or hydroisomerized anddewaxed using the process disclosed in U.S. Pat. No. 6,013,171,6,080,301 or 6,165,949. These patents are incorporated herein byreference for their disclosures of processes for treatingFischer-Tropsch synthesized hydrocarbons and the resulting products madefrom such processes.

Example 1

A multiple impregnation process is used to form a Co/Re catalystsupported on Al₂O₃. Separate batches of impregnation solutions (withdifferent concentrations) are used for each impregnation. Thecomposition of each impregnation solution is as follows: Impregnationsolution A contains 31.0% by weight cobalt nitrate and 2.8% by weightperrhenic acid. Impregnation solution B contains 29.8% by weight cobaltnitrate and 2.7% by weight perrhenic acid. Impregnation solution Ccontains 38.7% by weight cobalt nitrate and 3.5% by weight perrhenicacid. Impregnation solution D contains 40.7% by weight cobalt nitrateand 3.6% by weight perrhenic acid. The following sequence of steps isused.

(1) The Al₂O₃ support (1.0 gram) is calcined at 650° C. for 1 hour. Thesupport has a Brunauer-Emmett-Teller (BET) surface area of 200 m²/g anda Barrett-Joyner-Halenda (BJH) pore volume of 0.69 cm³/g.

(2) A first impregnation is conducted using 0.7 ml of impregnationsolution A to provide a total loading of 7.9% by weight Co and 1.2% byweight Re.

(3) The catalyst is dried at 90° C. for 12 hours, and then calcined byincreasing the temperature to 250° C. at a rate of 5° C. per minute andthen maintaining the temperature at 250° C. for 2 hours.

(4) The catalyst from step (3) has a BET surface area of 183 m²/g and aBJH pore volume of 0.57 cm³/g.

(5) A second impregnation is conducted using 0.57 ml of impregnationsolution B to provide a total loading of 13% by weight Co and 2.0% byweight Re.

(6) The catalyst is dried at 90° C. for 12 hours, and then calcined byincreasing the temperature to 250° C. at a rate of 5° C. per minute andthen maintaining the temperature at 250° C. for 2 hours.

(7) The catalyst from step (6) has a BET surface are of 162 m²/g, and aBJH pore volume of 0.48 cm³/g.

(8) A third impregnation is conducted using 0.48 ml of impregnationsolution C to provide a total loading of 19% by weight Co and 2.9% byweight Re.

(9) The catalyst is dried at 90° C. for 12 hours, and then calcined byincreasing the temperature to 250° C. at a rate of 5° C. per minute andthen maintaining the temperature at 250° C. for 2 hours.

(10) The catalyst from step (9) has a BET surface area of 144 m²/g and aBJH pore volume of 0.41 cm³/g.

(11) A fourth impregnation is conducted using 0.41 ml of impregnationsolution D with the result being a total loading of 25% by weight Co and3.6% by weight Re.

(12) The catalyst is dried at 90° C. for 12 hours, and then calcined byincreasing the temperature to 250° C. at a rate of 5° C. per minute andthen maintaining the temperature at 250° C. for 2 hours.

(13) A chemisorption test is conducted with the results being 6.2% Codispersion.

The pore volume and surface area data collected in the above-indicatedsynthesis are disclosed in FIG. 10.

Example 2

A single batch of impregnation solution is used for the followingimpregnations. The impregnation solution contains a saturated solutionof cobalt nitrate to which perrhenic acid is added. The followingprocedure is used.

(1) The Al₂O₃ support (1 gram) is calcined at 650° C. for 1 hour. Thesupport has a BET surface area of 200 m²/g and a BJH pore volume of 0.69cm³/g.

(2) A first impregnation is conducted using 0.69 ml of impregnationsolution to provide a total loading of 11.0% by weight Co and 1.7% byweight Re.

(3) The catalyst is dried at 90° C. for 12 hours, and then calcined byincreasing the temperature to 250° C. at a rate of 5° C. per minute andthen maintaining the temperature at 250° C. for 2 hours.

(4) The pore volume is assumed to be 0.52 cm³/g.

(5) A second impregnation is conducted using 0.66 ml of impregnationsolution to provide a total loading of 18% by weight Co and 2.8% byweight Re.

(6) The catalyst is dried at 90° C. for 12 hours, and then calcined byincreasing the temperature to 250° C. at a rate of 5° C. per minute andthen maintaining the temperature at 250° C. for 2 hours.

(7) The pore volume is assumed to be 0.435 cm³/g.

(8) A third impregnation is conducted using 0.63 ml of impregnationsolution to provide a total loading of 24% by weight Co and 3.6% byweight Re.

(9) The catalyst is dried at 90° C. for 12 hours, and then calcined byincreasing the temperature to 250° C. at a rate of 5° C. per minute andthen maintaining the temperature at 250° C. for 2 hours.

(10) The pore volume is assumed to be 0.39 cm³/g.

(11) A fourth impregnation is conducted using 0.61 ml of impregnationsolution with the result being a total loading of 28% by weight Co and4.2% by weight Re.

(12) The catalyst is dried at 90° C. for 12 hours, and then calcined byincreasing the temperature to 250° C. at a rate of 5° C. per minute andthen maintaining the temperature at 250° C. for 2 hours.

(13) A chemisorption test indicates a 6.3% Co dispersion. The catalysthas a BET surface area of 107 m²/g and a BJH pore volume of 0.28 cm³/g.

Portions of the sample from the foregoing synthesis are used to continueCo loading to 35% and 40% using the foregoing method.

Example 3

A Fisher-Tropsch reaction is conducted in a microchannel reactor. Themicrochannel reactor contains one process microchannel. The processmicrochannel has a height of 0.51 mm, a width of 0.7 cm, and a length of5.1 cm. The process microchannel contains 0.2 gram of a Co/Re catalystwhich is supported on Al₂O₃. The Co/Re molar ratio is 21. The catalystis prepared using a multi-impregnation method to achieve a 30% by weightloading of Co, and a 4.5% by weight loading of Re. The metal dispersionin the catalyst is 5.4%. The catalyst is in the form of particulatesolids having a particle size in the range of 177-250 microns. Thesolids are packed in the process microchannel. The process microchannelis cooled with an adjacent heat exchanger to the extent that thetemperature gradient within the catalyst is less than 5° C.

The reactor is operated at 20 atmospheres with a GHSV of 12520 hr⁻¹which corresponds to 0.26 second contact time. At 224° C. the COconversion is 50% and the methane selectivity is 10%. The pressure isincreased to 35 atmospheres and the initial CO conversion is increasedto 65%, and the methane selectivity is reduced to 6.8%. These resultsare shown in FIG. 14. Analysis of a liquid/wax sample from the productindicates that the chain growth probability is as high as 0.93.

The process is conducted at different operating pressures ranging from10 to 40 atmospheres, but at the same temperature (225° C.) and contacttime (0.26 second). The results are indicated in FIG. 15. The resultsindicate that the methane selectivity is reduced from 12% to 6.5% whenthe system pressure increases from 10 atmospheres to 40 atmospheres.

The process is conducted at 250° C. with the results being indicated inFIG. 16. Referring to FIG. 16, the process achieves a CO conversion of70% with the selectivity to methane being 10%.

The process is repeated with the contact time being reduced to 0.1second (GHSV=33, 180 hr⁻¹) at a pressure of 35 atmospheres and atemperature of 226° C.

The results are indicated in FIG. 17 which shows a CO conversion of 63%and a selectivity to methane of 10.5%.

Example 4

Two 30% Co-4.5% Re/Al₂O₃ catalysts are tested in a Fischer-Tropschsynthesis reaction. One of the catalysts is made using intercalcinationsteps. The other catalyst is made without intercalcination steps. Thecatalyst made with the intercalcination steps is made using thefollowing procedure. The support is impregnated with just enoughsaturated cobalt nitrate and perrhenic acid in water solution to fillits pores. The impregnated support is then heated at 90° C. for 14hours, then heated to 300° C. at 5° C./min and held at 300° C. for threehours for calcination before cooling to room temperature. This procedureis repeated four times to achieve the desired Co and Re loading.

The catalyst made without the intercalcination steps is made using thefollowing procedure. The support is impregnated with just enoughsaturated cobalt nitrate and perrhenic acid in water solution to fillits pores. The impregnated support is then heated to 90° C. and kept at90° C. for 14 hours before cooling to room temperature. This procedureis repeated four times to achieve the desired Co and Re loading. Afterthe last impregnation step the catalyst is heated to 350° C. at a rateof 10° C. per minute and then held at 350° C. for three hours beforebeing allowed to cool to room temperature.

The Fischer-Tropsch reaction is conducted in a microchannel reactorcontaining 5 process microchannels. The process microchannels have thedimensions of 1.5 mm height, 0.635 cm width and 2.54 cm length. Eachprocess microchannel contains about 0.15 gram of catalyst. The catalysthas a particle size in the range of 150 to 250 microns. The processmicrochannels are cooled using an adjacent heat exchanger. The reactionis conducted using a reactant composition that contains 63.89 mol %hydrogen, 32.1 mol % carbon monoxide and 4.01 mol % nitrogen. The inletgage pressure 20.4 atmospheres. The reactor is operated isothermally atthe temperature indicated in FIG. 18. The weight hourly space velocity)for carbon monoxide (mass of carbon monoxide fed per unit mass ofcatalyst per hour) is 4.9. The results are indicated in FIG. 18.

While the invention has been explained in relation to various detailedembodiments, it is to be understood that various modifications thereofwill become apparent to those skilled in the art upon reading thespecification. Therefore, it is to be understood that the inventiondisclosed herein is intended to cover such modifications as fall withinthe scope of the appended claims.

1. A microchannel reactor comprising at least one microchannel, the atleast one microchannel comprising at least one catalyst, the catalystcomprising a composition represented by the formulaCoM¹ _(a)M² _(b)O_(x) wherein M¹ is Fe, Ni, Ru, Re, Os, or a mixture oftwo or more thereof; M² is Li, B, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Sc, Y,La, Ac, Ti, Zr, La, Ac, Ce or Th, or a mixture of two or more thereof; ais a number in the range of zero to about 0.5; b is a number in therange of zero to about 0.5; and x is the number of oxygens needed tofulfill the valency requirements of the elements present.
 2. Themicrochannel reactor of claim 1 wherein the catalyst comprises Cosupported on alumina, the Co loading being at least about 5% by weight.3. The microchannel reactor of claim 1 wherein the catalyst comprises Cosupported on alumina, the Co loading being at least about 25%.
 4. Themicrochannel reactor of claim 1 wherein the catalyst comprises Cosupported on alumina, the Co dispersion being at least about 3%.
 5. Themicrochannel reactor of claim 1 wherein the catalyst is in the form ofparticulate solids.
 6. The microchannel reactor of claim 1 wherein thecatalyst is coated on interior walls of a microchannel, grown oninterior walls of a microchannel, or coated in situ on a fin structure.7. The microchannel reactor of claim 1 wherein the catalyst is supportedby a support structure made of a material comprising an alloy comprisingNi, Cr and Fe, or an alloy comprising Fe, Cr, Al and Y.
 8. Themicrochannel reactor of claim 1 wherein the catalyst is supported on asupport structure having a flow-by configuration, a flow-throughconfiguration, or a serpentine configuration.
 9. The microchannelreactor of claim 1 wherein the catalyst is supported on a supportstructure having the configuration of a foam, felt, wad, fin, or acombination of two or more thereof.
 10. The microchannel reactor ofclaim 1 wherein the catalyst is supported on a support structure havinga flow-by configuration with an adjacent gap, a foam configuration withan adjacent gap, a fin structure with gaps, a washcoat on a substrate,or a gauze configuration with a gap for flow.
 11. The microchannelreactor of claim 1 wherein the catalyst is supported on a supportstructure in the form of a fin assembly comprising at least one fin. 12.The microchannel reactor of claim 11 wherein the fin assembly comprisesa plurality of parallel spaced fins.
 13. The microchannel reactor ofclaim 11 wherein the fin has an exterior surface and a porous materialoverlies at least part of the exterior surface of the fin, the catalystbeing supported by the porous material.
 14. The microchannel reactor ofclaim 13 wherein the porous material comprises a coating, fibers, foamor felt.
 15. The microchannel reactor of claim 11 wherein the fin has anexterior surface and a plurality fibers or protrusions extend from atleast part of the exterior surface of the fin, the catalyst beingsupported by the protrusions.
 16. The microchannel reactor of claim 11wherein the fin has an exterior surface and the catalyst is: washcoatedon at least part of the exterior surface of the fin; grown on at leastpart of the exterior surface of the fin from solution; or deposited onat least part of the exterior surface of the fin using vapor deposition.17. The microchannel reactor of claim 11 wherein the fin assemblycomprises a plurality of parallel spaced fins, at least one of the finshaving a length that is different than the length of the other fins. 18.The microchannel reactor of claim 11 wherein the fin assembly comprisesa plurality of parallel spaced fins, at least one of the fins having aheight that is different than the height of the other fins.
 19. Themicrochannel reactor of claim 11 wherein the fin has a cross sectionhaving the shape of a square, a rectangle, or a trapezoid.
 20. Themicrochannel reactor of claim 11 wherein the fin is made of a materialcomprising: steel; aluminum; titanium; iron; nickel; platinum; rhodium;copper; chromium; brass; an alloy of any of the foregoing metals; apolymer; ceramics; glass; a composite comprising polymer and fiberglass;quartz; silicon; or a combination of two or more thereof.
 21. Themicrochannel reactor of claim 1 wherein the catalyst comprises Co and asupport, the catalyst being made by the process comprising: (A)impregnating the support with a composition comprising Co to provide anintermediate catalytic product; (B) calcining the intermediate catalyticproduct formed in (A); (C) impregnating the calcined intermediateproduct formed in (B) with a composition comprising Co to provideanother intermediate catalytic product; and (D) calcining the anotherintermediate catalytic product formed in (C) to form the catalyst, thecatalyst having a Co loading of at least about 25% by weight.
 22. Aprocess for conducting a Fischer-Tropsch reaction in a microchannelreactor, the microchannel reactor comprising a plurality of processmicrochannels and a plurality of heat exchange channels, the heatexchange channels extending lengthwise at right angles relative to thelengthwise direction of the process microchannels, the processcomprising: flowing reactants comprising CO and H₂ in the processmicrochannels in contact with a Fischer-Tropsch catalyst to form areaction product comprising one or more aliphatic hydrocarbons, thecatalyst comprising cobalt supported on an alumina support and being inthe form of particulate solids, the cobalt loading being at least about25% by weight; exchanging heat between the process microchannels and aheat exchange fluid in the heat exchange channels, the heat exchangefluid undergoing a phase change in the heat exchange channels.
 23. Theprocess of claim 22 wherein the reactants enter the processmicrochannels and the product exits the process microchannels, thetemperature of the reactants entering the process microchannels beingwithin about 200° C. of the temperature of the product exiting theprocess microchannels.
 24. The process of claim 22 wherein the moleratio of H₂ to CO is in the range of about 0.8 to about
 10. 25. Theprocess of claim 22 wherein the reactants further comprise H₂O, CO₂, ahydrocarbon of 1 to about 4 carbon atoms, or a mixture of two or morethereof.
 26. The process of claim 22 wherein the heat exchange fluidundergoes partial boiling in the heat exchange channels.
 27. The processof claim 22 wherein the reactants and product flow in the processmicrochannels in a first direction, and the heat exchange fluid flows inthe heat exchange channels in a second direction, the second directionbeing cross current relative to the first direction.
 28. The process ofclaim 22 wherein the heat exchange fluid comprises air, steam, water,carbon dioxide, gaseous nitrogen, a gaseous hydrocarbon or a liquidhydrocarbon.
 29. The process of claim 22 wherein the heat exchange fluidcomprises water, the water undergoing partial boiling in the heatexchange channels.
 30. The process of claim 22 wherein the catalystfurther comprises Re, Ru or a mixture thereof.
 31. The process of claim22 wherein the process microchannels have a bulk flow path comprisingabout 5% to about 95% of the cross sections of such processmicrochannels.
 32. The process of claim 22 wherein the contact time ofthe reactants and/or product with the catalyst is up to about 2000milliseconds.
 33. The process of claim 22 wherein the temperature of thereactants entering the process microchannels is in the range of about150° C. to about 270° C.
 34. The process of claim 22 wherein thepressure within the process microchannels is at least about 5atmospheres.
 35. The process of claim 22 wherein the space velocity forthe flow of the reactants and product in the process microchannels is atleast about 1000 hr.⁻¹
 36. The process of claim 22 wherein the pressuredrop for the flow of the reactants and product in the processmicrochannels is up to about 10 atmospheres per meter of length of theprocess microchannels.
 37. The process of claim 22 wherein the heatexchange fluid flows in the heat exchange channels, the pressure dropfor the heat exchange fluid flowing in the heat exchange channels beingup to about 10 atmospheres per meter of length of the heat exchangechannels.
 38. The process of claim 22 wherein the conversion of CO is atleast about 50%, the selectivity to methane in the product is about 25%or less, and the yield of product is at least about 35%.
 39. The processof claim 22 wherein the catalyst comprises particulate solids with aparticle size in the range of about 1 to about 1000 μm.
 40. The processof claim 22 wherein the product comprises hydrocarbons boiling at atemperature at or below about 350° C. at atmospheric pressure.
 41. Theprocess of claim 22 wherein the product comprises hydrocarbons boilingat or above a temperature of about 350° C. at atmospheric pressure. 42.The process of claim 22 wherein the product comprises a middledistillate.
 43. The process of claim 22 wherein the product comprises atleast one olefin.
 44. The process of claim 22 wherein the productcomprises a normal paraffin, isoparaffin, or mixture thereof.
 45. Theprocess of claim 22 wherein the product is further processed usinghydrocracking, hydroisomerizing or dewaxing.
 46. The process of claim 22wherein the product is further processed to form a lubricating base oilor a diesel fuel.
 47. The process of claim 22 wherein the product flowsout of the microchannel reactor and subsequent to the product flowingout of the microchannel reactor a regenerating fluid flows through theprocess microchannels in contact with the catalyst, the residence timefor the regenerating fluid in the process microchannels being from about0.01 to about 1000 seconds.
 48. The process of claim 22 wherein eachprocess microchannel has an internal dimension of up to about 10 mm. 49.The process of claim 22 wherein each heat exchange channel has aninternal dimension of up to about 10 mm.
 50. The process of claim 22wherein the process microchannels and heat exchange channels are made ofa material comprising: aluminum; titanium; nickel; copper; an alloy ofany of the foregoing metals; steel; monel; inconel; brass; a polymer;ceramics; glass; a composite comprising polymer and fiberglass; quartz;silicon; or a combination of two or more thereof.
 51. The process ofclaim 22 wherein the process microchannels and heat exchange channelsare made of stainless steel.
 52. The process of claim 22 wherein themicrochannel reactor comprises a microchannel reactor core, a reactantheader and a product footer.
 53. The process of claim 52 wherein themicrochannel reactor further comprises a heat exchange header and a heatexchange footer.
 54. The process of claim 52 wherein the processmicrochannels and the heat exchange channels are positioned in themicrochannel reactor core.
 55. The process of claim 52 wherein themicrochannel reactor core comprises layers of the process microchannelsand layers of the heat exchange channels aligned one above another orside by side.
 56. The process of claim 22 wherein each processmicrochannel has a cross section having the shape of a square,rectangle, circle or semi-circle.
 57. The process of claim 22 whereineach process microchannel has a cross section having the shape of arectangle.
 58. The process of claim 22 wherein each process microchannelhas a width and a length, the width tapering from a relatively smalldimension to a relatively large dimension over the length of the processmicrochannel.
 59. The process of claim 22 wherein each processmicrochannel has a width in the range up to about 3 meters, and a lengthin the range up to about 10 meters.